1. Cross-Reference
This application relates to a pending application Ser. No. 768,928 filed Feb. 15, 1977 and application Ser. No. 768,810 filed Feb. 15, 1977, now U.S. Pat. No. 4,072,927 and both assigned to the assignee of this application.
2. Field of the Invention
The invention relates to an electronic circuit for detecting phase differences between two cyclic signals and more specifically to such a circuit for monitoring the condition of a pneumatic tire for a vehicle.
3. Description of the Prior Art
The tire pressure monitoring system in application Ser. No. 768,810, now U.S. Pat. No. 4,072,927 employs a tire pressure operated switch which is open when the tire pressure is normal and which is closed when the pressure is abnormal; hence, it is difficult to check the condition of the circuit and the switch contacts when the tire pressure is normal. Further, the system, as disclosed, is incapable of providing a wheel speed signal.